Ethics

So today I've been thinking about ethics. Einstein said that there's relativity only in physics, but not in ethics, but I don't think I agree any longer. It's just that having become this nihilistic person has made me forget ethics all together. If we're all here just for some time, as if borrowing the world for some years whilst we realize our ambitions, and then we leave leaving not even a trace of ourselves, then what's the point? I guess I've accepted long ago that there's no purpose, and that's hard because it makes me reckless in a way where nothing really seems too much. There is no limit, who really cares if I fuck my life up royally when eventually none of it will matter? My grandmother told me today about the factory in which she worked many years ago, and how all the people she worked with our dead now, and that really gets to you. To realize that all those stories you've just heard about their youth, well, they're scratched. Those people are dead and their lives never mattered. So I guess what I'm saying is why bother with ethics if this is insignificant. Okay, I guess ethics towards some things does matter, like respecting other people's rights to life, because otherwise the world would just become utter chaos, but if it's things that affect only you, then why do we keep judging? I have a 19 year old girl friend who is sleeping, or was, whatever it is now, with a 55 year old man. And I guess that sounds wrong in some way and it's hard to process for me due to the fact that I've known this girl since we were children and I would have never imagined that this is where we'd end up, but the more I think about it, there's nothing wrong with anything she's doing. Fine, he's a wealthy minister involved in some dirty business and also the father of her friend, but maybe it just sounds wrong (at least it would have to me if I were even a little younger) because we've been instilled these ideas. Because if I think about it, there is nothing really that wrong with it, and why not? We're all going to die anyway so why are we, or me, trying to be so correct? Why am I so afraid to become something different from what I am? It's just sex, and it's just life, and it's just timeline that we essentially rent for our lifetime, but at the end it perishes into nothingness and never matters.
I guess ethics is relative, or in a way maybe even inexistent , just some human invention created to limit us, scare us off and control, get into our minds and make sure that no one goes too far.